Originally Posted by
Cardio 
After using an external esata drive with various models of Comcast DVR's branded Comcast, Cisco, SA or Motorola I have found that:
An external drive larger than 500GB will
not function correctly, if at all.
It may format, at least on a Cisco RNG200HD, the latest box, but you will get various errors and space over 500 GB is not even recoginized. I have been able to get a 750GB drive to work, for a time, but the functionality is still unreliable and the space over 500GB is not available.
The brand of HD is not an issue, nor is the speed of the drive 7200RPM~5400RPM. The brand of external enclosure may be, as the SATA I/O interface may vary somewhat from one brand to another. This should not be if they were all designed to the specifications of the interface but this does not appear to be the case. But the bottom line is that you will never get a drive larger than 500GB to work reliabily.
Comcast has no real information on this size limitation,, Surprise,,,,or even knows what you are talking about usually. Call them and ask, they just look down the "answer list" not find one and say something absurd. SA does not release any information on their publicly available literature either. I don't know if this limitation is part of the DVR's hardware programming or in the software of the Guide interface. We have just received the "new" Comcast Guide in Houston and I have not yet tried a larger drive using it. I will soon and will post what I find. When I asked Comcast's advance tech service they said "the new guide contained many new features". I thanked them for the useful information.
You lose all recorded programming if you change the external drive then reattach the previous one. Each time a drive is attaced it is formated if it's directory does not match the directory on the DVR. This also makes it impossibe to replace a full external drive with a new one and then later retach the 1st drive to play archived material on it.
A rather senseless limitation and typical of cable TV providers. It is difficult to understand the poor performance of huge companies; selecting horrible pieces like their REMOTE CONTROLS (purchased in millions), Cable boxes that are, at best, very low quality and stupid Guide implementation, the "new" Comcast guide is, in most respects, inferior to the previous antique one ....... until you consider that they are all virtual monoplies with no real competition. Satellite is not without its problems but I am about to go to Dish and forget cable. With a Dishnetwork DVR, 622,722,922 at least maybe others, you can add up to a 1TB external drive..........BUT they charge you a fee ($69) to turn on the esata port allowing you to do so. Charge you to attach your own drive!!
Please excuse the rant but I have fought this problem for years.